A86: Re: calculation error

To: assembly-86@lists.ticalc.org
Subject: A86: Re: calculation error
From: Cheetah17@aol.com
Date: Sat, 31 Oct 1998 09:28:37 EST
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org

   As an off-subject side note, I was very surprised this summer that the Mu
Alpha Theta (math competition society) national convention allowed any type of
calculator to be used.  The TI-92 hasn't been allowed at any other competition
besides the national one.
   And symbolic manipulation would be nice. Or maybe something that just left
answers in fractional for instead of decimal form in fraction form for
answers.

electrum@tfs.net (David Phillips) writes:

>  Speaking of symbolic, I remember that you were working on symbolic
>  manipulation for the 86.  I would am very interested in this and would like
>  to know how far you got, if at all.  A symbolic add-on for the calculator
>  certainly seems possible, especially with all the OS hooks that TI left in.
>  It even seems reasonable that it could be done transparently from the OS,
>  not even a separate program, but this might be way too much work.
>  
>  The TI-92 is too well known, and banned on almost (if not all) major and
>  minor math tests and competitions, and in most math classes as well.  The
>  TI-89 is allowed on most of the tests, but not all (the ACT comes to mind).
>  I don't want to start a debate over the 89, but I feel that TI did a very
>  poor job of converting it to the smaller case.  The software that would
have
>  worked well in the full size case (never used it, but I'd sure think it
>  would) doesn't work very well at all in a smaller one that is lacking many
>  buttons and a qwerty keyboard.  IMHO, TI should have completely redesigned
>  the interface to be more like the 85/86.  But I digress...
>  
>  I like the 86 better, and I use the 86 all the time, whereas the 89 stays
at
>  home.  Most tests do not require you to clear your memory, and the 86 is
>  already approved on all tests that allow graphing calculators, so symbolic
>  software for an already great calculator would rock!  I'd be more than
happy
>  to help anyone in this huge project...
>  
>  -----Original Message-----
>  From: Jimmy Mårdell <yarin@acc.umu.se>
>  To: assembly-86@lists.ticalc.org <assembly-86@lists.ticalc.org>
>  Date: Friday, October 30, 1998 9:46 PM
>  Subject: Re: A86: calculation error
>  
>  
>  >
>  >At 21:05 1998-10-30 -0500, you wrote:
>  >>
>  >>has anyone else noticed that when doing math calculations, sometimes the
>  >>answer will be 4.000000000001 or 3.999999999999 instead of 4 (4 is just
an
>  >>example)? in other words, it's off by the smallest value possible.  any
>  ideas
>  >>why?
>  >
>  >I don't see what this has to do with assembly, but the answer is
>  >pretty easy. First you can try calculating (1/3+1/3+1/3)-1 on any
>  >non-symbolic calculator, and you will get the anwer -1E-14 or some
>  >such instead of 0. The reason is that a computer (and calculator)
>  >uses a limited storage space for numbers (unlimited memory is
>  >very hard to find :) ), and thus rounding errors occur. In the
>  >case above you add .333+.333+.333 = .999, and then -1 = -0.001.
>  >
>  >--
>  >Real name:     Jimmy Mårdell
>  >Email:         mailto:yarin@acc.umu.se
>  >Homepage:      http://www.acc.umu.se/~yarin/
>  >
>  >Icarus Productions homepage: http://icarus.ganymed.org/